A conventional ventilating and air-conditioning apparatus using a heat pump for a bathroom has worked this way: A first heat exchanger of the heat pump radiates or absorbs heat to/from the air taken in from outside the bathroom, and then blows out the air into the bathroom. A second heat exchanger of the heat pump absorbs or radiates heat from/to air evacuated from the bathroom to the outdoors. The bathroom has been thus air-conditioned (refer to, e.g. Patent Document 1).
There is another conventional ventilating and air-conditioning apparatus. A heat pump is split into an outdoor unit and an indoor unit. A heat exchanger placed in the outdoor unit absorbs or radiates heat from/to the open air, and a heat exchanger placed in the indoor unit radiates or absorbs heat to/from the air in a bathroom, which is thus air-conditioned (refer to, e.g. Patent Document 2).
As discussed above, various ventilating and air-conditioning apparatus using a heat pump for a bathroom have been proposed. The bathroom air-conditioner disclosed in Patent Document 1 collects heat from air evacuated from the bathroom to the outdoors for air-conditioning the bathroom. However, the heat exchanger disclosed in Patent Document 1 cannot collect 100% of the heat from the evacuated air, so a part of the heat (energy of cooled air) having been used for the air-conditioning of the bathroom leaks to the outdoors. The leak incurs heat loss, which results in a lower thermal efficiency.
The bathroom air-conditioner disclosed in Patent Document 2, on the other hand, leaks a smaller amount of the heat having been used for the air-conditioning of the bathroom. However, since the heat pump is separated into the indoors and the outdoors of the bathroom, piping work for refrigerant to travel through is needed in order to connect the inside to the outside of the bathroom, so that installing work becomes inefficient. On top of that, this air-conditioner needs a space for the outdoor unit.    Patent Document 1: Unexamined Japanese Patent Application Publication No. 2005-180712    Patent Document 1: Unexamined Japanese Patent Application Publication No. 2002-349930